Due to @printf being a macro, it does not accept a format string that has been passed as a variable. myvec = randn(4) n = length(myvec) outstring = "Beginning of string with some numbers: " for i = 1:n outstring = outstring*"%-12.3g" end outstring = outstring*"\n" @printf(outstring, myvec...) I…

It’s been a long-standing issue and I hope it is resolved one day. I’ve been calling libc’s printf directly sometimes. In other situations, the definition print_formatted(fmt, args...) = @eval @printf($fmt, $(args...)) comes in handy but is very slow. You can get an idea of how performance is affe…

https://github.com/JuliaIO/Formatting.jl perhaps. Seems that https://github.com/JuliaIO/Formatting.jl/pull/30 is needed for 0.6 though.

That seems to solve the problem nicely, thank you :slight_smile:

Thanks, in my intended application I will happily pay the performance penalty as long as it’s less than about 0.1s. Your solution seems to solve the problem just fine without the need for an additional package, thanks!

I think that a native function would be preferable instead of a package or the @eval solution.

I am personally not very fond of Formatting.jl - not enough lean A short (and clean i hope) solution can be to gen closure with a macro according to the classical show signature import Printf macro gprintf(fmt::String) :((io::IO, arg) -> Printf.@printf(io, $fmt, arg)) end # can be used like …

still can’t use variable format strings with @printf in julia 1.9 :frowning: julia> using Printf julia> fmt = "%d" "%d" julia> @printf fmt 16 ERROR: LoadError: ArgumentError: First argument to `@printf` after `io` must be a format string Stacktrace: [1] var"@printf"(__source__::LineNumberNode, _…

thanks so much @Paul_Soderlind ! since format is not exported, and so isn’t documented , here’s specifically what i got to work: julia> using Printf julia> w=9 9 julia> fmt = Printf.Format("%$(w)d") Printf.Format{Base.CodeUnits{UInt8, String}, Tuple{Printf.Spec{Val{'d'}}}}(UInt8[0x25, 0x39, 0x64]…

What do you mean by “isn’t documented”? It is, in fact, documented. You have a link to its documentation in your post.

[image] Using a variable to format printf not allowed? New to Julia Like @Barget said, try the ? operator: help?> Printf.Format Printf.Format(format_str) Create a C printf-compatible format object that can be used for formatting values. The input format_str can in…

Printf with variable format string

General Usage

fatteneder May 22, 2023, 5:54pm 12

Topic		Replies	Views
Using a variable to format printf not allowed? New to Julia pretty-printing	9	1036	May 23, 2023
Using @printf to generate strings from format in Variable (maybe even in older Julia versions) General Usage	4	503	February 15, 2022
How to repeat the format in @printf? General Usage io	27	5316	March 16, 2023
How to use @sprintf with "parametric" format string? General Usage formatting , printf	5	1063	April 1, 2024
Compiled sprintf? General Usage formatting	3	935	April 28, 2018

Printf with variable format string

Related topics